Gemology Information

Emerald is the green gemstone variety of the mineral Beryl. Beryl is beryllium aluminium silicate - Be3Al2Si6O18.

Beryl occurs in many other colours, with shades dependent on the impurities that Mother Nature has mixed into its otherwise clear formula. Blue beryl is known as aquamarine. Pink shades of beryl are known as Morganite. Yellows are often simply called yellow beryl and golden beryl. The term bixbite refers to red beryl, a variation that's even rarer than emeralds. There is also a green beryl, colour given by iron content but this green beryl is not considered to be an emerald.

Emerald’s green colour occurs when pure, colourless beryl contains either chromium or vanadium, or a combination of both.

MOHS HARDNESS: 7.5-8 A hard stone, but subject to care because of internal liquid filled inclusions and fractures.

CHEMICAL COMPOSITION: Be 3 Cr 2 Si 6 O 18. Emeralds structure replaces the Aluminium present in the Beryl formula for Chromium present in Colombian Emeralds

REFRACTIVE INDEX: o=1.577, e=1.583 (+/- .017)
(The angle light is bent travelling through a gemstone)

DENSITY (SPECIFIC GRAVITY): 2.68-2.78
(The number of times heavier a gemstone is compared to water)

Emerald crystals are hexagonal in nature.  Large Emerald deposits are currently mined in Colombia, Brazil, and Zambia (Other deposits are found in Madagascar, India, Pakistan, Afghanistan, Russia, Australia, United States). The Zambian and Brazilian Emeralds are typically coloured due to the presence of vanadium, whereas Colombian Emeralds usually attain their tint from the presence of chromium. Chromium is the rare Midas element of gemstones: its presence also gives rubies their fiery redness.

The natural Emeralds that are being mined nowadays are in fact relics of geologic events that happened deep in the Earth’s crust, hundreds of millions of years ago.

In nature, chromium and vanadium, don't form anywhere close to deposits of Beryl; so the only way to make genuine Emerald is to smash the Earth's crust violently enough to throw Chromium / Vanadium and Beryl together, muddle them up, bury the lot and let nature take its course.

A glance through the magnifying-glass or microscope into the interior of an emerald tells us something about the eventful genesis of this unique gem: here we see small or large fissures; here the sparkle of a mini-crystal or a small bubble; here shapes of all kinds. While the crystals were still growing, some of these manifestations had the chance to 'heal', and thus the jagged three-phase inclusions typical of Colombian emeralds were formed: cavities filled with fluid, which often also contain a small bubble of gas and some tiny crystals.

Because the creation of an emerald is so necessarily violent we seldom see large emeralds with good colour and good transparency. The complex geology, the fiery eruptions and combination of rare minerals that comprise the ‘raw’ ingredients of emerald means that only occasionally was Mother Nature able to satisfy all the requirements in order for a gem quality Emerald crystal to grow.

Emeralds are at least twenty times rarer than diamonds. In the finest grades will sell for the same or above per-carat price as diamonds. Emeralds are readily available in lesser grades and even very large sizes, but are extremely rare in fine grades in any size.

Emerald can form in a wide range of green and green-blue shades, and generally the greener the stone the more valuable it is. The world's finest come from Colombia, and their exceptional transparency, fire and colour set the standards that other Emeralds are judged by. The country's mines also produce rarities like Trapiche Emeralds (trapiche is a grinding wheel), with a 6-rayed star emanating from the centre of the stone that is caused by dark carbon impurities.